Today we are going to discuss the performance of Nvidia’s multi-GPU configurations built with two and three overclocked GeForce GTX 670 graphics cards. Besides, we will also compare the performance of Nvidia GeForce HGTX 680 against AMD Radeon HD 7970 GHz Edition (emulated by overclocking) running the latest existing drivers.

Our previous review covered three proprietary GeForce GTX 670 graphics cards from Gigabyte, Palit and Zotac. Having collected so many graphics cards, including a reference GeForce GTX 670 too, we couldn’t help testing them in multi-GPU configurations. It is not often that we can build a 3-way SLI subsystem that may be expected to ensure a very high level of performance, at least theoretically. Besides that, we are going to compare a GeForce GTX 680 with a Radeon HD 7970 GHz Edition (simulated by overclocking a regular HD 7970) with the latest drivers from Nvidia and AMD. We’ve got some interesting results to share, so read on!

Testbed Configuration and Testing Methodology

Every card was tuned to the clock rates of the Zotac version, namely 1098/6608 MHz. The Gigabyte GTX 670 Ultra Durable went into the topmost PCI Express slot of our Intel Siler DX79SI mainboard. The reference card occupied the second slot and the bottom slot was given to the Zotac. The slots worked at x16+x8+x8 speed due to the mainboard’s limitations. As for our 2-way SLI configuration, it was built out of the Gigabyte in the first slot and the Zotac in the second, both slots working at their full speed (x16+x16).

The former’s clock rates were reduced to those of the reference GeForce GTX 680, i.e. 1006/6008 MHz, whereas the latter was overclocked to the level of the AMD Radeon HD 7970 GHz Edition (1050/6000 MHz).

So, we’ll see how faster the new Radeon is and whether it can beat the fastest GeForce.

All participating graphics cards were tested in a system with the following configuration:

In order to lower the dependence of the graphics cards performance on the overall platform speed, I overclocked our 32 nm six-core CPU with the multiplier set at 37x, BCLK frequency set at 125 MHz and “Load-Line Calibration” enabled to 4.625 GHz. The processor Vcore was increased to 1.46 V in the mainboard BIOS:

Hyper-Threading technology was enabled. 16 GB of system DDR3 memory worked at 2 GHz frequency with 9-10-10-28 timings and 1.65V voltage.

The test session started on June 22, 2012. All tests were performed in Microsoft Windows 7 Ultimate x64 SP1 with all critical updates as of that date and the following drivers:

The latest Catalyst drivers didn’t boost the performance of the Radeon HD 79xx graphics cards that much, which was definitely not the case with the new GeForce driver version 304.38. Except for two-three applications from the list of utilized benchmarks, the performance in all other tests improved stably by 2~3%, and in Crysis 2, Batman: Arkham City and all synthetic tests the improvement was as high as 5% or more in individual test modes and test resolutions. On top of that they also fixed the bug in Total War: Shogun 2 game, so that all GeForce GTX 6xx cards now run much better (up to +60%) in this game. So, it would be fair to day that Nvidia is well prepared to welcome the new AMD Radeon HD 7970 GHz edition properly.

The graphics cards were tested in two resolutions: 1920x1080 and 2560x1440. The tests were performed in two image quality modes: “Quality+AF16x” – default texturing quality in the drivers with enabled 16x anisotropic filtering and “Quality+ AF16x+MSAA 4(8)x” with enabled 16x anisotropic filtering and full screen 4x or 8x antialiasing if the average framerate was high enough for comfortable gaming experience. We enabled anisotropic filtering and full-screen anti-aliasing from the game settings. If the corresponding options were missing, we changed these settings in the Control Panels of Catalyst and GeForce drivers. We also disabled Vsync there. There were no other changes in the driver settings.

The list of games and applications used in this test session includes two popular semi-synthetic benchmarking suites, one technical demo and 15 games of various genres:

S.T.A.L.K.E.R.: Call of Pripyat (DirectX 11) – version 1.6.02, Enhanced Dynamic DX11 Lighting profile with all parameters manually set at their maximums, we used our custom cop03 demo on the Backwater map;

If the game allowed recording the minimal fps readings, they were also added to the charts. We ran each game test or benchmark twice and took the best result for the diagrams, but only if the difference between them didn’t exceed 1%. If it did exceed 1%, we ran the tests at least one more time to achieve repeatability of results.